Toggle press



Dec. 14, 1965 SOURCE OF COMPRESSED AIR SOURCE OF COMPRESSED AIR 0. LEOPOLD TOGGLE PRESS Filed Sept. 18, 1965 [llllHIIH I! I INVENTOR Otto Leopold ATTORNEYS United States Patent Ofitice 3,222,913 Patented Dec. 14, 1965 Claims. (01. 72 429 The present invention relates to a toggle press, i.e., a press in which the plunger or ram is moved by means of a toggle linkage.

For economic reasons, small and medium size presses are frequently constructed as manually operated devices, the arrangement being such that the press plunger is actuated by means of a toggle linkage. In order to obtain as large an operating force as possible, the toggle joint, sometimes referred to as a knuckle joint, is brought to its end position in which the two pivotally connected links are substantially in alignment with each other. This, however, has the drawback that the operation of such a press is, in many cases, very tiring, particularly when the work pieces being operated are not of uniform size. For example, if the work pieces are constituted by a plurality of parts that are to be riveted together, the total height of the parts may vary from operation to operation, depending on the thickness of the individual parts. This, too, will result in non-uniform riveting, because the end force ultimately exerted by the plunger when the toggle linkage is in its end position will fluctuate a good deal.

It is, therefore, an object of the present invention to provide what is basically a manually operated toggle .press which is so constructed that even a small operating force will produce a constant, and adjustable, pressure exerted by the ram in its end position and with this object in view, the present invention resides mainly in a press in which the idler or no-load movement of the plunger, necessary for allowing inserting and placing of the Work piece, is effected by means of a toggle linkage, which may be hand-operated, whereas the actual work stroke is effected automatically by means of a fluid pressure drive, the latter acting on the plunger with a substantial mechanical advantage.

More particularly, the present invention resides in a toggle press which comprises a support, a plunger movably mounted on the support, a toggle linkage interposed between the support and the plunger for moving the latter from an inoperative position to a position just short of its operative position which corresponds to a position of the toggle linkage which is just short of its dead center position, fluid pressure means interposed between the support and the toggle linkage for moving the latter with respect to the support, which fluid pressure means act on the toggle linkage with a substantial mechanical advantage, and means operatively associated with the toggle linkage for actuating the fluid pressure means when the linkage is just short of its dead center position, thereby to cause the fluid pressure means to move the toggle linkage while the same is in its dead center position, and, through the intermediary of the dead center toggle linkage, to move the plunger from just short of its operative position to its final operative position.

Additional objects and advantages of the present in vention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a longitudinal sectional view of a toggle press according to the present invention, taken substantially on line 1-1 of FIGURE 2.

FIGURE 2 is a horizontal sectional view taken substantially on line 22 of FIGURE 1.

Referring now to the drawing, the same shows a press according to the present invention. The press comprises a main support 1 of which only the upper part, which carries the ram or plunger 5 and the moving means associated therewith, is shown. The lower part of the support 1 which carries the stationary platen or die cooperating with the plunger head 5a is conventional and therefore not illustrated.

The top of the support 1 carries two eccentric sleeves 2 which are freely rotatable with respect to the support 1 and which are connected to each other via a lever 7 which comprises two arms 7a connected together by a pin 7b, the arms 7a being non-rotatably connected to the sleeves 2, respectively. The sleeves 2 serve as a rotatable bearing for a shaft 4; due to the eccentricity of the sleeves, the axis of shaft 4 is spaced from the axis about which the sleeves 2 rotate with respect to the support 1. A hand lever 3 is non-rotatably connected to the shaft 4 by means of a set screw 3a. The hand lever 3 is connected to the plunger 5 by means of a toggle link 6 which is pivotally connected to the lever 3 by means of a pin 26 and to the plunger by means of a further pin 21. The lever 3 is provided with an operating handle 3b by means of which the lever 3 can be pivoted about the axis of shaft 4, thereby to operate the toggle linkage.

The left end of lever 7 is pivotally connected to a compressed air drive 8 comprising a cylinder which is pivotally attached to the support 1, a cylinder cover 12a which closes off the upper end of the cylinder 12, a piston 13 which is slidably arranged in the cylinder, a piston rod 13a which is connected to the piston 13, which passes through the cover 12a, and which is pivotally connected to pin 71) interconnecting the two arms 7a, a buffer sleeve 14, and a return spring 15 interposed between the piston 13 and the cylinder cover 12a. The cylinder 12 is in communication, via the pivotal mount which attaches the cylinder to the housing 1, with a control valve 9 which serves to establish, via conduit means 9a, communication between the interior of the cylinder and a suitable source of fluid pressure, the latter being shown schematically only. The valve 9 also serves to vent the interior of the cylinder 12, the arrangement being such that when the valve 9 blocks the passage of compressed air from the source of pressure fluid, it places the interior of cylinder 12 in communication with the atmosphere, whereas this communication with atmosphere is closed when the valve 9 is in a position in which the interior of the cylinder 12 is in communication with the source of compressed air. The valve 9 has a control rod 11, the latter being actuated by a valve actuator lever 10 which is nonrotatably mounted on the shaft 4 by means of a set screw 10a.

Also shown is a stationary abutment 16 which cooperates with a stop surface 30 of lever 3.

The toggle press operates as follows:

FIGURE 1 shows the starting position of the parts. In order to operate the press, the lever 3 is pivoted in clockwise direction until the toggle link 6 is close to its dead center position. During this rotation, the plunger 5 goes through an idle or no-load stroke, represented by the distance a and reaches a position just short of its final operative position. During the last millimeters of the movement of the lever 3 until just before the stop surface 3c engages the abutment 16, the valve actuator lever 10 will engage the right-hand end of the valve control rod 11, thereby opening the valve 9. This will result in compressed air being fed into the cylinder 12. The piston 13 will then be driven upwardly and rotate the lever 7 in clockwise direction; this will cause the sleeves 2, and with them the eccentrically positioned shaft 4, to be rotated about the axis of the sleeves 2. The shaft 4, and with it the now dead center toggle linkage, and through the intermediary thereof, the plunger 5, will then be moved downwardly throughout the distance b, which represents the actual work stroke of the plunger. The toggle link 6, which is in its dead center position, will act as a rigid coupling between the shaft 4 and the plunger 5, so that during its work stroke b, the plunger is moved exclusively under the influence of the drive 8. It will be appreciated that the force with which the plunger 5 presses on the work piece (not shown) supported by the platen will be constant throughout the work stroke b, because the transmission, i.e., the lever ratio, between the drive 8 and the plunger 5 will remain unchanged.

Here it will be noted that lever 7 and eccentric sleeve 2 coact to form a bell crank lever whose axis is that of the sleeves 2; the lever arm with which the drive 8 acts will be the distance between the axis of pin 7b and the axis of sleeves 2, while the lever arm acting on the plunger will be the distance between the axis of sleeves 2 and the axis of the shaft 4. The lever ratio will, in practice, he of the order of approximately 10 to 1, so that the drive 8 will act on the toggle linkage with a substantial mechanical advantage.

The force which the plunger exerts at the end of the work stroke can be varied by adjusting the air pressure at which the drive 8 is operated; this can, in practice, be accomplished by means of a pressure reduction valve.

Upon completion of the operation, the lever 3 is pivoted in counterclockwise direction. The valve actuator lever 10 will immediately disengage itself from the right-hand end of the valve control rod 11, so that the valve 9 will be closed and the cylinder 12 be vented. The return spring 15 brings the parts of the drive 8 back to their starting position.

The full length of the available work stroke b need not always be used; in practice, only part of the stroke will be used during stamping and riveting operations, although the full Work stroke might be used during other types of operations, e.g., die punching. Consequently, only very small quantities of compressed air will be used despite the large pressure which is exerted by the plunger 5 at the end of the useful work stroke.

One major advantage of the present invention is that the pressure which the plunger exerts at the end of the stroke can be made to be substantially higher than was heretofore the case with simple, low-cost presses.

According to another feature of the present invention, the lever 3 can be operated automatically, for example, by means of a suitable compressed air drive which, since the same will not be called upon to operate durni g the actual work stroke, can be quite small. This additional compressed air drive is shown schematically only at 30.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. A toggle press comprising, in combination:

( a pp (b) a plunger movably mounted on said support;

(c) a toggle linkage interposed between said support and said plunger for moving the latter from an inoperative position to a position just short of its operative position which corresponds to a position of said toggle linkage which is just short of its dead center position;

((1) fluid pressure means interposed between said support and said toggle linkage for moving the latter with respect to said support, said fluid pressure means acting on said toggle linkage with a substantial mechanical advantage; and

(e) means operatively associated with said toggle linkage for actuating said fluid presure means when said linkage is just short of its dead center position, thereby to cause said fluid pressure means to move said toggle linkage while the same is in its dead center position, and, through the intermediary of the dead center toggle linkage, to move said plunger from just short of its operative position to its final operative position.

2. A toggle press as defined in claim 1 wherein said actuating means comprise a valve which, in its open position, places said fluid pressure in communication with a source of fluid medium under pressure and an actuating lever coupled to said toggle linkage for opening said valve when said linkage is just short of its dead center position.

3. A toggle press as defined in claim 1 wherein said toggle linkage comprises a lever rotata-bly mounted on said support, a toggle link pivotally connected to said lever and to said plunger, and means for rotating said lever.

4. A toggle press as defined in claim 3 wherein said means for rotating said lever comprise a handle.

5. A toggle press as defined in claim 3 wherein said lever is rotatably mounted within sleeve means which themselves are rotatably mounted on said support, the axis about which said lever rotates within said sleeve means being spaced from the axis about which said sleeve means rotate with respect to said support, and wherein said fluid pressure means is connected to said sleeve means for rotating the same about their own axis.

6. A toggle press as defined in claim 5 wherein said fluid pressure means is connected to said sleeve means via a lever arm whose length is substantially greater than the distance between the axis of said sleeve means and the axis about which said lever rotates within said sleeve means.

7. A toggle press as define-d in claim 6 wherein the ratio of the length of said lever arm to said distance between said axes is of the order of approximately 10 to l.

8. A toggle press as defined in claim 7 wherein said fluid pressure means comprise return spring means for returning said sleeve means to their original position upon venting of said fluid pressure means.

9. A toggle press comprising, in combination:

(a) a support;

(b) a plunger mounted on said support for reciprocatory movement relative thereto between an inoperative position and an opera-tive position;

(0) a toggle linkage comprising a lever and a toggle link pivotally connected to said lever;

(d) means pivotally connecting said plunger to said link at a point thereof spaced from the pivotal connection between said lever and said link;

(e) sleeve means rotatably mounted on said support for rotation about a sleeve axis;

(f) a shaft non-rotatably connected to said lever at a point thereof spaced from the pivotal connection betwen said lever and said link, said shaft being rotatably mounted on said sleeve means for rotation about a shaft axis which is spaced from said sleeve axis;

(g) means for rotating said toggle linkage lever about said shaft axis until said toggle linkage is just short of its dead center position, said plunger, in such position of said toggle linkage, occupying a position just short of its operative position;

(h) lever arm means non-rotatably connected at one end thereof to said sleeve means;

(i) fluid pressure means pivotally mounted on said support and pivotally connected to the other end of said lever arm means, the length of said lever arm means being substantially greater than the distance between said sleeve axis and said shaft axis;

(j) valve means for placing said fluid pressure drive means in communication with a source of fluid medium under pressure; and (k) valve actuator means carried by said shaft for rotation therewith for opening said valve means when said toggle linkage is just short of its dead center position, thereby to cause said fluid pressure means to rotate said sleeve means and hence move said shaft and with it said toggle linkage and said plunger until the latter is in its final operative position. 10. A toggle press as defined in claim 9 wherein said fluid pressure means comprise a cylinder, 2. piston slidably' arranged in said cylinder, piston rod means interconnecting said piston and said other end of said lever arm means, and a return spring interposed between said References Cited by the Examiner UNITED STATES PATENTS 1,463,229 7/1923 Simmons 7841 1,750,144 3/1930 Wisti 78-41 2,633,094 3/1953 Muller 100-272 RICHARD J. HERBST, Primary Examiner.

CHARLES W. LANHAM, G. P. CROSBY, Examiners. 

1. A TOGGLE PRESS COMPRISING, IN COMBINATION: (A) A SUPPORT; (B) A PLUNGER MOVABLY MOUNTED ON SAID SUPPORT; (C) A TOGGLE LINKAGE INTERPOSED BETWEEN SAID SUPPORT AND SAID PLUNGER FOR MOVING THE LATTER FROM AN INOPEATIVE POSITION TO A POSITION JUST SHORT OF ITS OPERATIVE POSITION WHICH CORRESPONDS TO A POSITION OF SAID TOGGLE LINKAGE WHICH IS JUST SHORT OF ITS DEAD CENTER POSITION; (D) FLUID PRESSURE MEANS INTERPOSED BETWEEN SAID SUPPORT AND SAID TOGGLE LINKAGE FROM MOVING THE LATTER WITH RESPECT TO SAID SUPPORT, SAID FLUID PRESSURE MEANS ACTING ON SAID TOGGLE LINKAGE WITH A SUBSTANTIAL MECHANICAL ADVANTAGES; AND (E) MEANS OPERATIVELY ASSOCIATED WITH SAID TOGGLE LINKAGE FOR ACTUATING SAID FLUID PRESSURE MEANS WHEN SAID LINKAGE IS JUST SHORT OF ITS DEAD CENTER POSITION, THEREBY TO CAUSE SAID FLUID PRESSURE MEANS TO MOVE SAID TOGGLE LINKAGE WHILE THE SAME IS IN ITS DEAD CENTER POSITION, AND, THROUGH THE INTERMEDIARY OF THE DEAD CENTER TOGGLE LINKAGE, TO MOVE SAID PLUNGER FROM JUST SHORT OF ITS OPERATIVE POSITION TO ITS FINAL OPERATIVE POSITION. 